Spark plug



Jan. 3, 1925. v 1,522,897 v A. MARSCHALEK SPARK PLUG Filed Dec. 23, 1922 WWW of parts by which the above objects are at Patented Jan. 13, 1925.

1,522,897 PATENT OFFICE.

ALEXANDER MARSGHALEK, OF EAST RUTHERFORD, NEW JERSEY.

SPARK PLUG.

Application filed December 23, 1922. Serial No. 608,658.

To all whom it may concern:

Be it known that I, ALEXANDER MAR- SGHALEK, a citizen of the United States, residing at East Rutherford, in the countyof Bergen and State of New Jersey, have 1n- .vented a certain new and useful Improvement in Spark Plugs, of which the followin is a specification.

he invention relates to spark-plugs employed in the ignition systems of internal combustion engines, and the object of the invention is to provide a spark-plug in which the flashes of light due to the passage of the spark may be easily observed while the plug is functioning, and which is simply con-- structed, may be inexpensively manufactured, and is reliably insulated, and durable and eflicient.

The invention consists in certain novel features of construction and arrangement tained, to be hereinafter described and claimed.

The accompanying drawings form a part of this specification and show the inventlon as it has been carried-out in practice. For

clearness. of illustration the drawings are on a greatly exaggerated scale.

Figure 1 is a side elevation of the 1mproved plug.

Figure 2 is a corresponding axial section, partly in elevation.

Fi ure 3' is a transverse section taken on the line 3-3 in Figure 2.

' Figure 4 is a plan view of the plug, seen from below. I Figure 5 is an elevation of the insulatmg and light conducting tube alone.

Similar reference numerals indicate the same partsin all the figures.

The base or body 10 of the plug has the usual screwthreaded extension or boss 11- at the lower end, of less diameter than the body and adapted to be screwed'into the head of the motor, not shown, and receives a copper gasket 12 as usual. Its upper end 13 is hex"- agonalto receive a wrench and is screwthreaded internally to receive a removable collar 14 adapted to be screwed therein by its hexagonal head 15. The interior of the collar 14 is also screwthreaded and is shaped to provide an annular cavity 16 arranged .to receiveasbestos or other i 17 compressed therein by a suitable packing gland -18.

, Extending axially of the body and through its collar and gland, is a thick-' walled tube 19 of clear colorless glass, preferably Pyrex or analogous heat-resisting glass. Its lower end terminates within the hollow lower end of the body and its upper end projects considerably above the gland 18.

Inclosed in and insulated by the tube is the central electrode 20. Its upper end 21 is screwthreaded and extends beyond the upper end of the tube 19 and through a yielding asbestos ring 22 and washer 23 and receives a nut 24. The lower end projects below the tube and carries an annular flange 25 of slightly larger diameter than the bore of the tube but considerably less than the outside diameter thereof. The flange 25 is separated from the tube by an asbestos ring 26 and serves as an abutment for the electrode in opposition to the nut 24. l/Vhen the latter is turned down the tube and electrode are firmly held together as one, with liberty for unequal expansion provided for by theyielding rings 22 and 26.

On the electrode 20 below the flange 25 is a neck 27 terminating in a circular termlnal or sparking head 28 lying in the same plane with and slightly separated from the head 28 is concentric to the tube, this "rela tive radial position is maintained in respect to any rotarymovements of the tube or of the electrode 20 axially mounted therein.

The tube is held against, axial movement by'the firm grasp thereon of the packin 17 in the cavity 16 compressed by the gland 18 and as an aid to the strong frictional grip thus afforded, the tube is provided with a roughened zone 31 produced as to present aportion of'the roughened 'surfaceto the packing 17 in all positions.

The extreme projecting upper and of the central electrode serves with the knurled nut 32 and nut 24 as a binding-post for the battery wire, not shown.

Thus arranged the light from each sparkflash traverses the transparent wall of the by the action of a sandblast or otherwise and so located ed by the arrow in Figure 1, and which isapproximately the usual angle of vision of an observer viewing the spark-plugs of an automobileengine when the hood is lifted. Experiment has shown that the desired refraction may be easily produced by ing upon the tube an annular swell or bulb 33 as shown in the drawings, and-this form is preferred by reason of its simplicity and easy production, but the annular prism may be otherwise formed, as for example, by

' properly designed angular grooves'or ridges analogous to those of the well-known Fresnel lens. (I

The improved plug offers the advantages of direct observation of the ignition spark light as distinguished from devices having an auxiliary gap in the sparking circuit; the latter merely indicates the flow of current which may or may not be producing an ef fective ignition spark, while in the improved plug the absence of the refracted light shows unerringly the condition and which of the several plugs is inoperative or performing imperfectly, due to faulty wiring, carbon deposition, or other cause.

As the surface of the tube is glassy smooth, deposition of carbon is slight, and

to clean the lower end of the tube it is only necessary to unscrew the collar 14- and with draw it with its attachedtube and electrode and remove any coating from the exposed surface by wiping.

Beside showing the passage of the igni tion spark, the improved plug indicates to the observer other conditmns, as, for exform ample, the quality of the mixture in the motor cylinder; if the proper mixture is being supplied the refracted light shows a bluish-white tinge, while if too rich, a smoky treddish hue is shown.

The glass tube ofl'ers perfect insulation, and the improved plug is eminently simple in construction and easily assembled; its parts are open for inspection and may be readily replaced if defective.

1. In a spark-plug, a body portion and a light-conducting member therein, an electrode extending continuously throu h sai member for cooperation with a fixe termi-' nal at the end of said body to form a sparkgap outside of said member, and means cooperating with the electrode for closing both ends of said member, said member having an angularly surfaced portion outside said body serving to refract the li ht angularly.

2. In a spark-plug, a ho y portion, a

member removably engaged therewith, an,

open-ended tubular light-conducting member held therein, andan electrode extended unbrokenly' through said light-conducting member, and means carried by the electrode for closing both ends of said tubular member, said tubular member having an annular swell outside said body, the light traversing said tubular member from the sparkflash at the end of the same being augmented and refracted by said swell.

3. In a spark plug, a body portion, a member removably engaged therein, an open-ended tubular light-conducting member having an angularly surfaced light-refracting portion outside said first-named member, and an electrode extended imbrokenly through said light-conducting member and supported by the latter. 7

In testimony that I claim the invention above set forth I afiix my signature.

ALEXANDER MARSCHALEK. 

